A film bulk acoustic wave device and a method of manufacturing the same

Abstract

This invention discloses a method for fabricating a thin-film bulk acoustic wave device, comprising etching a first cavity on a silicon substrate, depositing a sacrificial layer within the first cavity, depositing a first electrode on the sacrificial layer and a portion of the substrate, and sequentially depositing a piezoelectric thin film, a second electrode, and a protective layer on the first electrode and another portion of the substrate in a single step, etching until the piezoelectric thin film is exposed, simultaneously etching to obtain a Q-value enhancement structure and an exposed second electrode, etching deposition vias and release holes on the piezoelectric thin film, depositing a first metal pad layer through the deposition vias to connect the first metal pad layer to the first electrode, depositing a second metal pad layer on the exposed second electrode, and etching the sacrificial layer through the release holes to obtain a second cavity, thereby obtaining the thin-film bulk acoustic wave device; the Q-value enhancement layer is etched from the protective layer by physical etching, such that the etching profile of the Q-value enhancement layer is controlled at 80-90°. This invention also discloses a thin-film bulk acoustic wave device fabricated using this method.

Description

Technical Field

[0001] This invention belongs to the field of bulk acoustic wave resonator technology, specifically relating to a thin-film bulk acoustic wave device and its fabrication method. Background Technology

[0002] With the rapid development of wireless communication technology, wireless signals are becoming increasingly congested, placing new demands on filters operating in the radio frequency (RF) region, including integration, miniaturization, low power consumption, high performance, and low cost. Traditional surface acoustic wave (SAW) filters, limited by frequency and power handling capabilities, are increasingly unable to meet these standards. Thin-film bulk acoustic wave (FBAR) filters, using bulk acoustic waves as the signal transmission medium, offer significantly higher power capacity, higher operating frequencies, superior Q-value performance, CMOS process compatibility, low loss, and low temperature coefficient compared to other filters, gradually becoming a hot topic in RF filter research.

[0003] With the rapid development of mobile communication technology, the market demand for high-frequency resonators and filters is increasing. Compared with traditional microwave ceramic resonators and surface acoustic wave resonators, thin-film bulk acoustic resonators (FBARs) have advantages such as small size, low loss, high quality factor, large power capacity, and high resonant frequency. Therefore, they have broad application prospects in related fields, especially in high-frequency communication, and have become a research hotspot in industry and academia. A thin-film bulk acoustic resonator (FBAR) is a device that uses acoustic resonance to achieve electrical frequency selection based on bulk acoustic wave theory. Its principle is to select the frequency through the vertical resonance of the piezoelectric material between the upper and lower thin-layer electrodes. By combining multiple thin-film bulk acoustic resonators, a filter structure can be formed.

[0004] The performance level of a filter is determined by its Factor of Merit (FOM), defined as FOM = Q * K²eff, where Q is the quality factor, which describes the vibration attenuation of the oscillator or resonator and characterizes the bandwidth of the resonator relative to its center frequency. It is related to the structure and manufacturing process of FBAR devices, and current FBAR filters have Q factors ranging from 2500 to 5000. K²eff is called the effective coupling coefficient, a property related to the properties of the piezoelectric thin film material.

[0005] Realizing the Q-value enhancement structure of a thin-film bulk acoustic resonator is a key process. The traditional fabrication method involves first depositing the Q-value enhancement structure layer on a piezoelectric thin film, followed by photolithography and etching. During the fabrication of this Q-value enhancement structure, a high-selectivity etching process is required to minimize damage to the piezoelectric thin film. Furthermore, to avoid excessively large etching profiles that could lead to breakage of subsequent deposits, such as the second electrode, the etching angle (etching profile) is often controlled within 40-60°, which fails to achieve the simulated Q-value enhancement effect. Summary of the Invention

[0006] This invention provides a method for fabricating a thin-film bulk acoustic wave device. The etching profile in the thin-film bulk acoustic wave device prepared by this method can reach 80-90°, thereby achieving the simulated Q-value improvement effect.

[0007] A method for fabricating a thin-film bulk acoustic wave device, comprising:

[0008] A first cavity is etched on a silicon substrate, a sacrificial layer is deposited within the first cavity, a first electrode is deposited on the sacrificial layer and a portion of the substrate, and a piezoelectric thin film, a second electrode, and a protective layer are sequentially deposited on the first electrode and another portion of the substrate in a single process. Etching begins on a portion of the protective layer until the piezoelectric thin film is exposed. Etching is performed on the other portion of the protective layer to obtain a Q-value enhancement structure and an exposed second electrode. Deposition vias and release holes are etched on the piezoelectric thin film. A first metal pad layer is deposited through the deposition vias, connecting the first metal pad layer to the first electrode. A second metal pad layer is deposited on the exposed second electrode. The sacrificial layer is etched through the release holes to obtain the second cavity, thereby obtaining a thin-film bulk acoustic wave device. The Q-value enhancement layer is etched from the protective layer using physical etching, with the etching profile of the Q-value enhancement layer controlled at 80-90°.

[0009] Since the Q-value boosting structure of this invention is located on the top layer, there is no need to consider the problem of making the etching profile angle slightly inclined to avoid the collapse of the Q-value boosting structure in order to support other components.

[0010] The method for etching the Q-value enhancement layer includes a Trimming physical etching process, resulting in an etching profile of 85-90°. The linewidth of the Trimming physical etching process is 1.5-4 μm.

[0011] The method of etching a Q-value enhancement layer from a protective layer by physical etching includes forming a first Q-value enhancement pattern, a second Q-value enhancement pattern, and a third Q-value enhancement pattern from the protective layer by physical etching. The three Q-value enhancement patterns are isolated from each other and have the same bottom, and the thickness of the bottom is at least 100 nm.

[0012] Before depositing the first cavity, the silicon substrate is ultrasonically cleaned with SPM solution, and the silicon substrate is oriented C(001). The silicon substrate is one or any combination of silicon, silicon carbide, sapphire, or ceramic.

[0013] The method for depositing the piezoelectric thin film is magnetron sputtering or MOCVD deposition, and the material of the piezoelectric thin film is aluminum nitride, doped aluminum nitride, zinc oxide, lithium nickelate, or lead zirconate titanate. The thickness of the piezoelectric thin film is 0.35-2 μm.

[0014] The cross-section of the first cavity is one of trapezoidal, triangular, rectangular, or square, or any combination thereof, and the lateral width of the first cavity is 30-500μm.

[0015] The cross-section of the second cavity is one of trapezoidal, triangular, rectangular, or square, or any combination thereof, and the lateral width of the second cavity is 30-500μm.

[0016] The present invention deposits a first electrode or a second electrode by means of thermal evaporation or magnetron sputtering. The material of the first electrode is one or any combination of molybdenum, gold, platinum, copper, aluminum, silver, titanium, tungsten or nickel, and the thickness of the first electrode is 300-3000 nm.

[0017] The material of the second electrode is one or any combination of molybdenum, gold, platinum, copper, aluminum, silver, titanium, tungsten or nickel, and the thickness of the second electrode is 300-3000 nm.

[0018] Methods for patterning the first and second electrodes include plasma etching, lift-off, or wet etching, resulting in electrode patterns with a lateral width of 50-600 μm.

[0019] This invention deposits a first metal pad layer or a second metal pad layer by means of thermal evaporation or magnetron sputtering. The material of the first metal pad layer or the second metal pad layer is one or any combination of molybdenum, gold, platinum, copper, aluminum, silver, titanium, tungsten, or nickel. The thickness of the first metal pad layer or the second metal pad layer is 300-3000 nm.

[0020] The method for patterning the first or second metal pad layer is the lift-off method.

[0021] The present invention also provides a thin-film bulk acoustic wave device prepared by the aforementioned method for preparing a thin-film bulk acoustic wave device.

[0022] This invention also provides a method for fabricating a thin-film bulk acoustic wave device, comprising:

[0023] A first cavity is etched on a silicon substrate, a sacrificial layer is deposited within the first cavity, a first electrode is deposited on the sacrificial layer and a portion of the substrate, a piezoelectric thin film and a second electrode are sequentially deposited on the first electrode and another portion of the substrate in a single process, and a portion of the second electrode is removed by dry etching to expose the piezoelectric thin film. A Q-boosting structure is etched on the second electrode, a protective layer is deposited on the Q-boosting structure, the piezoelectric thin film and the second electrode, and etching begins from a portion of the protective layer until the piezoelectric thin film is exposed. The second electrode is exposed by etching on another portion of the protective layer, and vias and release holes are etched on the piezoelectric thin film. A first metal pad layer is deposited through the vias, connecting the first metal pad layer to the first electrode. A second metal pad layer is deposited on the exposed second electrode, and the sacrificial layer is etched through the release holes to obtain the second cavity, thereby obtaining a thin-film bulk acoustic wave device. The Q-boosting layer is etched from the second electrode by physical etching, and the etching profile of the Q-boosting layer is controlled at 80-90°.

[0024] The method of etching a Q-value enhancement layer from a protective layer by physical etching includes forming a first Q-value enhancement pattern, a second Q-value enhancement pattern, and a third Q-value enhancement pattern from the protective layer by physical etching. The three Q-value enhancement patterns are isolated from each other and have the same bottom, and the thickness of the bottom is at least 100 nm.

[0025] The first Q-value enhancement pattern and the third Q-value enhancement pattern are located on both sides of the Q-value enhancement layer, and the second Q-value enhancement pattern is located between the first Q-value enhancement pattern and the third Q-value enhancement pattern. The outer side of the first Q-value enhancement pattern is aligned with the outer side of the first cavity, and the outer side of the second Q-value enhancement pattern is aligned with the outer side of the first cavity.

[0026] The present invention also provides a thin-film bulk acoustic wave device prepared by the aforementioned method for preparing a thin-film bulk acoustic wave device.

[0027] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0028] This invention employs a one-step molding process for a piezoelectric thin film, a second electrode, and a protective layer, replacing the traditional multi-deposition process. This simplifies the process flow and avoids the risk of impurities introduced through multiple film depositions. A trimming physical etching process is used to obtain a Q-value-enhanced structure with an etching profile of 80-90°, truly realizing the transformation from design simulation to physical prototype. This invention can significantly improve the performance of thin-film bulk acoustic wave devices and increase product market competitiveness. Attached Figure Description

[0029] Figure 1 In the cavity fabrication provided in Embodiment 1 of the present invention, 101 is a substrate and 102 is a first cavity;

[0030] Figure 2 In the preparation of the sacrificial layer provided in Embodiment 1 of the present invention, 101 is the substrate and 102-1 is the sacrificial layer;

[0031] Figure 3 In the fabrication of the first electrode provided in Embodiment 1 of the present invention, 101 is a substrate, 102-1 is a sacrificial layer, and 103 is the first electrode;

[0032] Figure 4 The piezoelectric thin film layer, second electrode and protective layer provided in Embodiment 1 of the present invention are deposited as follows: 101 is the substrate, 102-1 is the sacrificial layer, 103 is the first electrode, 104 is the piezoelectric thin film layer, 105 is the second electrode and 106 is the protective layer.

[0033] Figure 5 In the fabrication of the second electrode provided in Embodiment 1 of the present invention, 101 is a substrate, 102-1 is a sacrificial layer, 103 is a first electrode, 104 is a piezoelectric thin film layer, 105 is a second electrode, and 106 is a protective layer.

[0034] Figure 6 In the fabrication of the Q-value enhancement structure provided in Embodiment 1 of the present invention, 101 is a substrate, 102-1 is a sacrificial layer, 103 is a first electrode, 104 is a piezoelectric thin film layer, 105 is a second electrode, 106 is a protective layer, and 107, 107-1, and 107-2 are Q-value enhancement structures.

[0035] Figure 7 The exposed second electrode provided in Embodiment 1 of the present invention is as follows: 101 is a substrate, 102-1 is a sacrificial layer, 103 is a first electrode, 104 is a piezoelectric thin film layer, 105 is a second electrode, 106 is a protective layer, 107 and 107-1, 107-2 are Q-value enhancement structures, and 108 is the exposed second electrode.

[0036] Figure 8 The piezoelectric thin film via etching provided in Embodiment 1 of the present invention is as follows: 101 is the substrate, 102-1 is the sacrificial layer, 103 is the first electrode, 104 is the piezoelectric thin film layer, 105 is the second electrode, 106 is the protective layer, 107 and 107-1, 107-2 are Q-value enhancement structures, 108 is the exposed second electrode, 109 is the first electrode Pad deposition via, 109-1 is the release hole, and the dashed line represents the section that is not visible below.

[0037] Figure 9The metal pad fabrication provided in Embodiment 1 of the present invention is shown below: 101 is the substrate, 102-1 is the sacrificial layer, 103 is the first electrode, 104 is the piezoelectric thin film layer, 105 is the second electrode, 106 is the protective layer, 107, 107-1, and 107-2 are Q-value enhancement structures, 108 is the exposed second electrode, 109 is the first electrode pad deposition via, 109-1 is the release hole, 110 is the metal pad connected to the first electrode, and 110-1 is the metal pad connected to the second electrode. The dashed line represents the section that is not visible below.

[0038] Figure 10 The example provided in Embodiment 1 of the present invention is a sacrificial layer release, where 101 is a substrate, 102-2 is the first cavity after the sacrificial layer is released, 103 is the first electrode, 104 is a piezoelectric thin film layer, 105 is the second electrode, 106 is a protective layer, 107 and 107-1, 107-2 are Q-value enhancement structures, 108 is the exposed second electrode, 109 is the first electrode Pad deposition via, 109-1 is a release hole, 110 is a metal Pad connected to the first electrode, 110-1 is a metal Pad connected to the second electrode, and the dashed line represents the section that is not visible below;

[0039] Figure 11 The piezoelectric thin film layer, second electrode deposition and fabrication provided in Embodiment 2 of the present invention are as follows: 101 is the substrate, 102-1 is the sacrificial layer, 103 is the first electrode, 104 is the piezoelectric thin film layer, and 105 is the second electrode.

[0040] Figure 12 In the Q-value enhancement structure provided in Embodiment 2 of the present invention, 101 is a substrate, 102-1 is a sacrificial layer, 103 is a first electrode, 104 is a piezoelectric thin film layer, 105 is a second electrode, and 106, 106-1, and 106-2 are Q-value enhancement structures.

[0041] Figure 13 In the preparation of the protective layer deposition provided in Embodiment 2 of the present invention, 101 is the substrate, 102-1 is the sacrificial layer, 103 is the first electrode, 104 is the piezoelectric thin film layer, 105 is the second electrode, 106 and 106-1, 106-2 are Q-value enhancement structures, and 107 is the protective layer.

[0042] Figure 14 In the preparation of the exposed second electrode provided in Embodiment 2 of the present invention, 101 is a substrate, 102-1 is a sacrificial layer, 103 is a first electrode, 104 is a piezoelectric thin film layer, 105 is a second electrode, 107 and 107-1, 107-2 are Q-value enhancement structures, 106 is a protective layer, and 108 is the exposed second electrode.

[0043] Figure 15For the piezoelectric thin film via etching provided in Embodiment 2 of the present invention, 101 is the substrate, 102-1 is the sacrificial layer, 103 is the first electrode, 104 is the piezoelectric thin film layer, 105 is the second electrode, 107 and 107-1, 107-2 are Q-value enhancement structures, 106 is the protective layer, 108 is the exposed second electrode, 109 is the first electrode Pad deposition via, 109-1 is the release hole, and the dashed line represents the section that is not visible below;

[0044] Figure 16 In the metal Pad fabrication provided in Embodiment 2 of the present invention, 101 is the substrate, 102-1 is the sacrificial layer, 103 is the first electrode, 104 is the piezoelectric thin film layer, 105 is the second electrode, 107 and 107-1, 107-2 are Q-value enhancement structures, 106 is the protective layer, 108 is the exposed second electrode, 109-1 is the release hole, 110 is the metal Pad connected to the first electrode, 110-1 is the metal Pad connected to the second electrode, and the dashed line represents the section that is not visible below the cross-section.

[0045] Figure 17 For the sacrificial layer release provided in Embodiment 2 of the present invention, 101 is a substrate, 102-2 is the first cavity formed after the sacrificial layer is released, 103 is the first electrode, 104 is a piezoelectric thin film layer, 105 is the second electrode, 107 and 107-1, 107-2 are Q-value enhancement structures, 106 is a protective layer, 108 is the exposed second electrode, 109-1 is a release hole, 110 is a metal Pad connected to the first electrode, 110-1 is a metal Pad connected to the second electrode, and the dashed line represents the section that is not visible below the cross-section. Detailed Implementation

[0046] This invention replaces the traditional multi-deposition process with a one-step forming process of piezoelectric thin film, second electrode, and protective layer. This simplifies the process and avoids the risk of introducing impurities through multiple film depositions. After integrating multiple film layers, a Q-value-enhanced structure with an etching profile of 80-90° can be obtained using a trimming physical etching process, truly realizing the transformation from design simulation to physical prototype.

[0047] Example 1

[0048] This invention provides a method for fabricating a thin-film bulk acoustic wave device, comprising:

[0049] (1) The silicon substrate 101 was ultrasonically cleaned with SPM solution. The silicon substrate orientation was C(001).

[0050] (2) Figure 1As shown, a first cavity 102 is formed on a silicon substrate 101 using a dry etching process. The first cavity etching process has an RF power of 1200 / 360W, a chamber pressure of 20mT, an SF6 / O2 etching gas flow rate of 200 / 30sccm, an etching rate of approximately 800nm / min, and a lateral width of 200μm.

[0051] (3) Figure 2 As shown, a phosphorus-containing silicon oxide layer of approximately 4 μm is deposited as a sacrificial layer 102-1 using PECVD, and then processed by CMP to form a sacrificial layer that fills the first cavity 102. The dishing between the sacrificial layer and the substrate 101 needs to be maintained at ±50 nm.

[0052] (4) Figure 3 As shown, a 30 nm aluminum nitride seed layer (not shown) and a 150 nm molybdenum layer are deposited on a CMP-treated substrate 101 using methods such as thermal evaporation or magnetron sputtering. The first electrode 103 is then formed by dry etching. The etching process for the first electrode is as follows: RF power 1000 / 10 W, chamber pressure 10 mT, etching gas SF6 / O2 flow rate 40 / 60 sccm, etching rate approximately 50 nm / min, and the lateral width of the first electrode 103 is 400 μm.

[0053] (5) Figure 4 As shown, magnetron sputtering or MOCVD methods are used in... Figure 3 Structurally, an 800 nm aluminum nitride piezoelectric thin film 104, a 200 nm molybdenum metallic layer 105, and a 200 nm scandium-doped aluminum nitride protective layer 106 are deposited. The growth process for the aluminum nitride piezoelectric thin film is as follows: Ar / N2 gas flow rate of 100 / 20 sccm, growth temperature of 200 °C, chamber pressure of 2.4 mT, target / RF power of 6000 / 145 W, and growth rate of approximately 1 nm / min. The sputtering process for the molybdenum metallic layer is as follows: Ar gas flow rate of 20 sccm, growth temperature of 200 °C, chamber pressure of 2.4 mT, target / RF power of 6000 W, and sputtering rate of approximately 6 nm / min. The growth process for the scandium-doped aluminum nitride piezoelectric thin film is as follows: Ar gas flow rate of 50 sccm, growth temperature of 200 °C, chamber pressure of 2 mT, target / RF power of 8000 / 15 W, and growth rate of approximately 2 nm / min. To minimize the impact of other factors on film deposition, the aluminum nitride piezoelectric film 104, the molybdenum metal 105, and the scandium-doped aluminum nitride protective layer 106 must be deposited in a single step.

[0054] (5) Figure 5As shown, the second electrode 105 and the protective layer 106 are patterned using a dry etching method. The etching process for the protective layer 106 is as follows: RF power 1000 / 500W, chamber pressure 8mT, etching gas BCL3 / CL2 flow rate 110 / 30sccm, and etching rate approximately 150nm / min. The etching process for the second electrode 105 is as follows: RF power 1000 / 100W, chamber pressure 8mT, etching gas SF6 / O2 flow rate 40 / 30sccm, and etching rate approximately 60nm / min. The lateral width of the second electrode and the protective layer is 400μm.

[0055] (6) Figure 6 As shown, a first Q-value enhancement pattern 107, a second Q-value enhancement pattern 107-1, and a third Q-value enhancement pattern 107-2 are formed on the protective layer 106 using a Trimming or IBE physical etching process. After etching, at least 100 nm of the protective layer remains below patterns 107 and 107-1. The outer sides of the Q-value enhancement structures 107 and 107-1 are aligned with the first cavity, with a linewidth of 2 μm and an etching profile of 80-90°. The lateral width of 107-2 is 50 μm. The Trimming physical etching process uses an argon ion beam current of 10 mA and a chamber pressure of 5 mT. During etching, the argon ion beam current is perpendicular to the substrate 101. The main purpose of using the Trimming physical etching process is to ensure the uniformity of the remaining protective layer thickness and that the etching profile meets the requirements.

[0056] (7) Figure 7 As shown, the second electrode is exposed on the protective layer 106 by dry etching or wet etching to form pattern 108. The RF power of the protective layer etching process is 1000 / 500W, the chamber pressure is 8mT, the flow rate of etching gas BCL3 / CL2 is 110 / 30sccm, and the etching rate is about 150nm / min.

[0057] (8) Figure 8 As shown, patterns 109 and 109-1 are formed on the piezoelectric layer 104 using either dry etching or wet etching methods. 109 is a deposition via for depositing the first electrode Pad, and 109-1 is a release via. The via etching process uses an RF power of 500 / 200W, a chamber pressure of 8mT, an etching gas Ar / Cl2 flow rate of 10 / 70sccm, and an etching rate of approximately 300nm / min.

[0058] (9) such as Figure 9 As shown, a first metal pad 110 and a second metal pad 110-1 are patterned using a lift-off process. The thickness of the first or second metal pad is 800 nm, and the first metal pad 110 is not connected to the second electrode 105.

[0059] (10) such as Figure 10 As shown, the sacrificial layer is removed through the sacrificial layer release hole 109-1 by dilute BOE immersion etching to form the cavity 102-2 required for the operation of the acoustic wave device. Figure 10 As shown, the marked area represents the etching profile angle. The method of this invention can control the profile angle to be 80-90°.

[0060] Example 2

[0061] This invention provides a method for fabricating a thin-film bulk acoustic wave device, comprising:

[0062] (1-3): Steps (1)-(3) are the same as steps (1)-(3) in Example 1.

[0063] (4) Using magnetron sputtering or MOCVD methods in Figure 3 An 800 nm aluminum nitride piezoelectric film 104 and a 200 nm molybdenum film 105 were deposited structurally. The aluminum nitride piezoelectric film was grown using an Ar / N2 gas flow rate of 100 / 20 sccm, a growth temperature of 200 °C, a chamber pressure of 2.4 mT, a target / RF power of 6000 / 145 W, and a growth rate of approximately 1 nm / min. The molybdenum film was sputtered using an Ar gas flow rate of 20 sccm, a growth temperature of 200 °C, a chamber pressure of 2.4 mT, a target / RF power of 6000 W, and a sputtering rate of approximately 6 nm / min. To minimize the influence of other factors on the film deposition, the aluminum nitride piezoelectric film 104 and the molybdenum film 105 were deposited in a single step. The molybdenum was removed using a dry etching method to form... Figure 11 pattern.

[0064] (5) Figure 12 As shown, patterns 107 and 107-1, 107-2 are formed on the second electrode 105 using Trimming or IBE physical etching processes. The etching depth is 100 nm. The Q-value enhancement structure 107 and 107-1 are aligned with the first cavity on the outside, with a linewidth of 2 μm and an etching profile of 80-90°. The lateral width of 107-2 is 50 μm. The Trimming physical etching process uses an argon ion beam of 14 mA and a chamber pressure of 5 mT. During etching, the argon ion beam is perpendicular to the substrate 101. The main purpose of using Trimming physical etching is to ensure the uniformity of the remaining protective layer thickness and that the etching profile meets the requirements.

[0065] (6) Figure 13 As shown, magnetron sputtering or MOCVD methods are used in... Figure 12A 100 nm aluminum nitride protective layer 106 was deposited structurally. The growth process of the aluminum nitride protective layer 106 was as follows: Ar / N2 gas flow rate of 100 / 20 sccm, growth temperature of 200℃, chamber pressure of 2.4 mT, target / RF power of 6000 / 160 W, and growth rate of approximately 1 nm / min.

[0066] (7-10): Steps (7)-(10) are the same as steps (7)-(10) in Example 1, such as Figure 14-17 As shown. Figure 17 As shown, the marked area represents the etching profile angle. The method of this invention can control the profile angle to be 80-90°.

Claims

1. A method of fabricating a film bulk acoustic wave device, characterized by, include: A first cavity is etched on a silicon substrate, a sacrificial layer is deposited within the first cavity, a first electrode is deposited on the sacrificial layer and a portion of the substrate, and a piezoelectric thin film, a second electrode, and a protective layer are sequentially deposited on the first electrode and another portion of the substrate in a single process. Etching begins on a portion of the protective layer until the piezoelectric thin film is exposed. Etching is performed on the other portion of the protective layer to obtain a Q-value enhancement structure and an exposed second electrode. Deposition vias and release holes are etched on the piezoelectric thin film. A first metal pad layer is deposited through the deposition vias, connecting the first metal pad layer to the first electrode. A second metal pad layer is deposited on the exposed second electrode. The sacrificial layer is etched through the release holes to obtain the second cavity, thereby obtaining a thin-film bulk acoustic wave device. The Q-value enhancement layer is etched from the protective layer using physical etching, with the etching profile of the Q-value enhancement layer controlled at 80-90°.

2. The method of manufacturing a film bulk acoustic wave device according to claim 1, wherein The physical etching method for the Q-value enhancement layer is the Trimming physical etching process, and the etching profile after etching is 85-90°.

3. The method for fabricating a thin-film bulk acoustic wave device according to claim 1, characterized in that, The linewidth of the Trimming physical etching process is 1.5-4μm.

4. The method for fabricating a thin-film bulk acoustic wave device according to claim 1, characterized in that, Before depositing the first cavity, the silicon substrate is ultrasonically cleaned with SPM solution. The silicon substrate is oriented C(001). The silicon substrate is one or any combination of silicon, silicon carbide, sapphire or ceramic.

5. The method for fabricating a thin-film bulk acoustic wave device according to claim 1, characterized in that, The method for depositing the piezoelectric thin film is magnetron sputtering or MOCVD deposition, and the material of the piezoelectric thin film is aluminum nitride, doped aluminum nitride, zinc oxide, lithium nickelate or lead zirconate titanate; the thickness of the piezoelectric thin film is 0.35-2 μm.

6. The method for fabricating a thin-film bulk acoustic wave device according to claim 1, characterized in that, The present invention deposits a first electrode or a second electrode by means of thermal evaporation or magnetron sputtering. The material of the first electrode is one or any combination of molybdenum, gold, platinum, copper, aluminum, silver, titanium, tungsten or nickel, and the thickness of the first electrode is 300-3000 nm. The material of the second electrode is one or any combination of molybdenum, gold, platinum, copper, aluminum, silver, titanium, tungsten or nickel, and the thickness of the second electrode is 300-3000 nm.

7. A thin-film bulk acoustic wave device prepared by the method of preparing a thin-film bulk acoustic wave device according to any one of claims 1-6.

8. A method for fabricating a thin-film bulk acoustic wave device, characterized in that, include: A first cavity is etched on a silicon substrate, a sacrificial layer is deposited within the first cavity, a first electrode is deposited on the sacrificial layer and a portion of the substrate, a piezoelectric thin film and a second electrode are sequentially deposited on the first electrode and another portion of the substrate in a single process, and a portion of the second electrode is removed by dry etching to expose the piezoelectric thin film. A Q-boosting structure is etched on the second electrode, a protective layer is deposited on the Q-boosting structure, the piezoelectric thin film and the second electrode, and etching begins on a portion of the protective layer until the piezoelectric thin film is exposed. The second electrode is exposed by etching on another portion of the protective layer, and vias and release holes are etched on the piezoelectric thin film. A first metal pad layer is deposited through the vias, connecting the first metal pad layer to the first electrode. A second metal pad layer is deposited on the exposed second electrode, and the sacrificial layer is etched through the release holes to obtain the second cavity, thereby obtaining a thin-film bulk acoustic wave device. The Q-boosting layer is etched from the second electrode by physical etching, and the etching profile of the Q-boosting layer is controlled at 80-90°.

9. The method for fabricating a thin-film bulk acoustic wave device according to claim 8, characterized in that, The method of etching a Q-value enhancement layer from a protective layer by physical etching includes forming a first Q-value enhancement pattern, a second Q-value enhancement pattern, and a third Q-value enhancement pattern from the protective layer by physical etching. These patterns are isolated from each other and have the same bottom, and the thickness of the bottom is at least 100 nm.

10. The method for fabricating a thin-film bulk acoustic wave device according to claim 9, characterized in that, The first Q-value enhancement pattern and the third Q-value enhancement pattern are located on both sides of the Q-value enhancement layer, and the second Q-value enhancement pattern is located between the first Q-value enhancement pattern and the third Q-value enhancement pattern. The outer side of the first Q-value enhancement pattern is aligned with the outer side of the first cavity, and the outer side of the second Q-value enhancement pattern is aligned with the outer side of the first cavity.

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